Eulerian-Lagrangian modeling of liquid-fueled rotating detonation with varied equivalence ratios

The application prospects of liquid-fueled rotating detonation engine (RDE) in the aerospace field are extensive. However, numerical simulations of liquid-fueled RDE, particularly for the non-premixed fuel and oxidant injection, are significantly lacking compared to pure gas-phase modeling efforts. Therefore, an Eulerian-Lagrangian model is established in the present study to elucidate the propagation characteristics of rotating detonation wave (RDW) supplied with liquid octane and oxygen-rich air. The fuel droplets, considered as the discrete phase, are described by the Lagrangian governing system to capture the movement and atomization process of droplets. The continuous gas-phase is described by the Euler equations. The detonation combustion flow field and the unsteady motion process of fuel particles in the combustor are depicted in detail. The effect of equivalence ratio on the detonation propagation characteristics is also analyzed. The numerical results show the fluctuations in the transient filling height of the oxidant and the detonation velocity, attributed to the detonation instability. Along the intersection of the rotating detonation front and the oblique shock wave, the oxidant trailing strip is found to penetrate the detonation product zone. As a result, part of the fuel does not participate in the reaction in the combustor. When the equivalence ratio increases above 1.3, the propagation of RDW transits from single-wave mode to dual-wave mode. This study demonstrates the complexity of propagation mechanism of RDW involving liquid fuel droplets.